Was hanging out with young up-and-coming coffee superstar Alex Powar today, and while I was mouthing-off with some coffee brewing spiel, Alex added, “Yeah… I mean, we call them coffee particles after all…”
The general definition of a “particle” can be said to be an effectively one-dimensional thing. It’s a point in space. It’s a dot. The function of a “particle” (generally) renders mass, volume, and surface-area effectively irrelevant.
But a coffee ‘ground’ or ‘grind’ or whatever-you-wanna-call-it is not a one-dimensional point/dot. It’s a three-dimensional thing. There’s an outside and an inside. Understanding coffee brewing requires understanding the relationship between dissolution of the solids on the surface of the coffee grinds and the solids _inside_ the coffee grinds. The stuff on the surfaces dissolves quickly, and diffuses into solution as soon as it dissolves. The stuff on the inside dissolves a little more slowly, and needs to move through and out of the coffee grinds before entering solution.
In daily life, most everything that is as small as a coffee ‘particle’ is treated mostly the same: salt, sugar, sand, ground pepper, paprika, dirt, the size of Texas Gov. Rick Perry’s brain, etc. These bits are small enough that the shape and size of individual particles are generally inconsequential in most common situations. There is, however, growing awareness of the size and shape of salt crystals, including research by food scientists trying to figure out how to make a saltier-tasting NaCl crystal in order to reduce sodium consumption in certain foods (notably, potato chips). But I digress.
Coffee bean fragments are not “particles.” They’re small, but the size and shape are indeed consequential… at least if you want to make good coffee.
So the question is: what do/should we call coffee bean fragments if not “particles?” Unless someone has a better idea, I’m going to start using the term “coffee fragments.”
Normally, I’d be happy with a water TDS reading like this. I’m not right now. Why? Because it’s the water at home, and one week ago, it was 40ppm TDS, which is 100ppm less exactly one week ago.
About 140 ppm (parts per million) TDS is, according to all the relevant literature, about ideal for brewing coffee. With our the ~40ppm water (we live 30 minutes south of San Francisco), I’ve dialed in my coffee brewing to fantastic flavor. Juicy acidity, sweet, balanced, fantastic. 40ppm is supposed to be a bit low, but it’s been great.
I made coffee on the morning of January 1st. It was (again) juicy, bright, and sweet. I made coffee that same evening for a couple friends. The coffee tasted embarassingly flat, and while it had most of the sweetness, it was missing the juicy-acidity, like as if the tweeters on my audio speakers suddenly cut out. (Perhaps) needless to say, my technique is very dialed-in with my home-lab setup.
My mind raced through all of the variables. I’d been brewing with lower water temperatures lately… maybe I needed to pump things up to higher temps? Tried that… no dice. The grinder is fine. It was the SAME coffee… could it change SO much in 8 hours? No way. So what could change all-of-a-sudden like that?
I had lent my Myron-L water conductivity meter (pictured) to a friend, but I got it back from her yesterday because I had to assume something had changed with the water coming out of our taps. Sure enough, it was 100 ppm higher than my last measurement.
Still… if 140 ppm is ideal, why can’t I get (any of) these coffees as delicious as I know they can be? Perhaps the nature of the 100 ppm could reveal some clues? I mean, if that +100 ppm (or mg/L if you wanna get more nerdy) of impurities are made up of more neutralizing or buffering compounds, it would make some sense. I’ll be doing some more testing. Stay tuned!
Instead of a top-5 or 10 or whatever, how’s about just a list?
Best Burger I Ate All Year : Intelligentsia Coffee & Tea Pasadena Cafe, December 7, 2011, because it was just fantastic. FYI, I had a fair number of burgers this year.
Best Coffee Blog : Roaster Project because I appreciate the blogger’s sharing his journey with us as he’s learning and experimenting and designing and building. Sharing is good.
Best coffee-person’s Flickr Feed : Three Sevens because it’s a great mix of coffee pics, personal stuff, and just the right amount of Instagrammy content (not too much, not too little).
Best Media Coverage Of Coffee By The Lame-Stream Media : CNBC’s “The Coffee Addiction”
Best coffee iPhone app : (this space intentionally left blank)
Best Climate By Government Test : Redwood City, California
Best Overhyped Company in Coffee : Handsome Coffee Roasters because nobody could possibly live up to the amount of hype these boys got? Make no mistake, HUGE love and respect for Handsome and what they do, but the coverage left such a mark on our retinas that it feels like they had a reality-show this year, even though they were never on TV.
Best Underhyped Company in Coffee : Gimme! Coffee because they’re doing way more awesomer coffee and admirable stuff this year than the push they got in the industry.
Best IT-GIRL of specialty coffee : Julie Housh
Best Coffee Video : “Betty’s Coffee”
Best Coffee Gadget/Gear : Baratza Virtuoso + Esatto
Best Humongous Multi-Story Roaster-Retailer Shop : Sightglass Coffee
Best Barista Objectification For A Great Charity : WBC Champion 2012 Calendar
Best Shortest Coffeeshop Name : I Do, Seoul, Korea
Best Groan-inducing Coffeeshop Name : Seventh Wave Coffee, Seoul, Korea
Best Coffee Industry Event : Barista Guild of America Camp Pull-A-Shot
Best Sprudge.com Post : #YesEqual
and the 2011 Official Best Phenomenon in Coffee: The Guest Barista Shift because the concept of the guest-shift quietly came into its own this year. From random reports from around the country and around the world, to the BGA EC doing guest-shifts throughout PDX, the idea of a barista traveling to a shop that they do not work at and… well… work, is a remarkable thing to be sure. Not only does this reveal a certain amount of trust among peoples, it also means that there’s enough skill out there that it’s even possible. Imagining such a thing happening just a few years ago is ludicrous, and now it’s everywhere. And completely under-the-radar, as if it was always supposed to be like that. I can think of little else that is as much a display of passion for the craft as it is a symbol of the best parts of the barista community and specialty coffee, for the reasons stated and for many others. It makes my heart happy.
See you in 2012!
It’s not a law, but the rule of thumb is +10°C _doubles_ the rate of chemical reactions*.
If we take the ‘typical’ rule of thumb for coffee brew water temperature, we get:
195-205°F = Δ5.6°C ∴ ±~56% change in reaction rates, and every 1°F represents approximately 5% change in the rate of reaction. Think about this when your brain are hyper-focused a scale while trying to get your 350g brew water weight precision down to 1.0g (which is 0.2%).
*-the classic rule of thumb on rules of thumb is that thumbtimes it’s true, thumbtimes it isn’t.
Summary & Links:
The PRESS RELEASE we read on the show
YouTube link: Bree (the most popular Barista in the Pacific Northwest)
ICE Coffee “C” Futures
“At The Cupping Table” with Trish and Mie from 49th Parallel.
Ethiopian Coffee “BladderGate” (more reading) LINK: Portafilter Podcast #58 interview with Getachew Mengistie
The future of the Keurig single-cup coffee system (LINK: SF Bay Coffee OneCup)
Our Top-5 list of the Most Fascinating Things in Specialty Coffee in 2011
Duration: 1h 31m 19s
Critical analyses of coffee brewing methods involves taking a close look at what happens to individual coffee particles through the course of the brew. Every brew method involves three notable steps: Wetting, extraction, and separation. For some methods, extraction and separation happen mostly simultaneously (i.e., drip brewing). For other methods like cupping, french press, or Clever dripper (among others), extraction happens in a relatively static environment with separation occurring only (or mostly) at the end. It’s important to note: separation always includes extraction, often with an accelerated or more forceful dynamic.
During such methods, the fact that separation of grinds and brewed product (the beverage) happen at the end of the brew also means that the separation is occurring when the risk of over-extraction is high. You could stir the hell out of a brew at the beginning, but the cross-over into over-extraction usually won’t happen until later in the brew time.
MOST french press brews out there in the world are woefully underextracted, and not representative of this brew method’s potential. Worse, high-sludge content due to sloppy or poor technique, contribute what can only be called “false body,” that is, mouthfeel that comes from the super-fine coffee particles in the brew, rather than from the coffee itself. This is even further exacerbated by very dark roasted coffees, for which the roasty-toasty-burnt flavors are so soluble that they dominate an otherwise weak and underextracted brew. Grinding approximately for drip and brewing for under 5 minutes is generally leaving desirable flavors out of your brew.
So to make a delicious french press is to make a properly extracted french press. To do that, there are three key elements to consider:
1) proper wetting
2) the static environment
3) the separation dynamic
*1) Proper wetting*
In order for extraction to happen efficiently, the coffee particles must be free of gas, and surrounded by water on all sides. If coffee grounds are floating, or intermixed with gaseous bubbles, one or both of these requirements aren’t met. Gentle stirring, a prolonged pour of brew water, or a light plunge of the filter screen will help fully wet the coffee.
*2) The static environment*
A static extraction is both good and bad for the quality of the beverage. It’s good because certain brew methods can inflict too much kinetic energy (read: turbulence) on the coffee grounds which causes the surfaces of the coffee grounds to extract too quickly. A more static environment allows the solubles to diffuse more naturally into the brew water. Conversely, a static environment can cause the water around the coffee grounds to become over-saturated with solubles, which slows down the osmosis effect necessary to get the solubles out of the coffee particles.
So the solution is to extend the brew time beyond what’s typical for a drip-style brew, and grind significantly coarser. If an ideal drip-grind peak particle size is approximately 800μm (0.8mm) in diameter, something around 1200μm (1.2mm) is great for french press. Why?
The longer brew time is necessary to correspond with the static brew environment. However, since a longer brew time would normally lead to over-extraction, reducing the overall surface-area to coffee-mass ratio helps reduce the proportion of over-extraction in the brew. Remember, because coffee grinds are not truly uniform in particle size (unless we physically separated them and removed outlying particle sizes), a coffee brew is always a mixture of “good” brew, overextraction, and underextraction. The overall better-quality brews are simply higher-proportions of “good’ brew than not. The smaller-than-peak grinds will overextract. The larger-than-peak grinds will underextract.
So if a drip brew with 800μm grind sizes is a 4-minute brew, and a french press is a 6-minute brew, and we wish to reduce the surface-area-to-mass ratio of the coffee grinds accordingly, we come to a 1200μm grind size.
Obviously a coffee particle is not a sphere, but the results are the same if you use any shape as a model:
Volume of a sphere = 4/3 * π * radius-cubed
If diameter = 0.8mm, volume = 0.268 cubic mm
If diameter = 1.2mm, volume = 0.905 cubic mm
Surface area of a sphere = 4π * radius-squared
If diameter = 0.8mm, surface area = 2.01 square mm
If diameter = 1.2mm, surface area = 4.52 square mm
Volume / Surface area
@0.80mm, 0.268/2.01 = 0.133
@1.20mm, 0.905/4.52 = 0.200
∴ 0.133 : 0.200 :: 4 minutes : 6 minutes
So grind coarse (about 1.2-1.5 mm diameter peak grind), and 6-8 minutes. Yes, really. Not only does this coarseness work in consort with the brew method, grinding this coarsely results in a smaller proportion of extra-fine particles.
It may help to very-gently stir-up the coffee grounds at the end before you plunge, so that the flavor compounds that diffused out of the grinds sitting at the bottom of the glass (which you’ll have if you were successful in your wetting) will be added to the mixture, rather than just sitting at the bottom of the glass.
*3) The separation dynamic*
The separation between grinds and resulting beverage should always be as gentle and low-kinetic-energy as possible, especially for brewing methods with a primarily static brew dynamic like french press. The particles at the end of a brew have already released the desirable flavor compounds. If you forcefully stir or squeeze the coffee particles at the end of the brew, you’re much more likely to add overextraction-flavors to the brew than otherwise.
So plunge gently. If you feel even the slightest resistance due to a layer of coffee grinds building under the plunger, back off gently and press on. If you forcefully press grounds downward in the glass with the plunger, you’re forcefully extracting those grounds. So don’t do it. You’re also forcing more super-fine coffee particles (a.k.a. fines or sludge) through the mesh if you plunge hard.
Otherwise, you know what to do. 60-70 grams of coffee per liter of water, and ~200°F (±5°F) brew water to start. Final point: technique (or method) is important, but quality of coffee, quality of grinder (uniform as possible), and quality (clean) water round-out the four pillars of great coffee brewing.
Let me know in the comments how this works out for you!
UPDATE 2014: This blog post refers to the previous sensory skills test. It was revised in 2013 to correct the Part 3 “trick question” issue. Now the concentrations from parts I and 2 are indeed carried over to Part 3. Leaving this post up for reference, but do understand the update. Mmmkay?
The SCAA Sensory Skills Test is out there. It’s touted as an objective test of your taste acuity, removing olfactory (aroma) to focus on your papillae. The problem is, the test is poorly designed and those who have the acuity often still fail. It was once required to pass this if you wanted to be a World Barista Championship taste judge, and it’s still part of the CQI Q-Grader exams. If you’re going to take this, study this guide first.
Part 1: Three different strength levels of Salt (table salt NaCL), Sweet (table sugar, sucrose), and Sour (citric acid) are presented in groups, for a total of nine solutions. Identify the strengths in order for each group (i.e., Salt 1, 2, & 3)
Part 2: The nine solutions from Part 1 are presented in random order. Identify the type (salt, sweet, sour) and the strength (1, 2, & 3).
Part 3: Eight mixtures of Salt, Sweet, and Sour are presented. Four are 2-part mixtures, four are 3-part mixtures. Identify each component type and the strength in each mixture.
If you can’t pass the test Parts 1 and 2, you’re on your own… you might be a non-taster and may want to consider this in your career choices.
Part 3, depending on how it’s presented to you, is likely a TRICK QUESTION.
The “trick” is that there are eight mixtures, four 2-parters and four 3-parters. That’s all fine. The misconception is that when you combine the tastes, your palate is confused by the mixtures somehow. THIS IS NOT TRUE.
THE PROBLEM :
What most instructors don’t tell you or don’t know themselves (and that the materials don’t explain), is that if you have a 2-part mixture, each component is now HALF the strength it was before. If Salt-1 is 1.0-grams-per-liter, and you dilute it with one part of Sweet 2 solution, the resulting solution is now 0.5-grams-per-liter… because the other half is the Sweet solution.
THEN, for THREE-PART solutions, each component is diluted by 66.6%. The 1.0 g/L Salt-1 is now 0.33 g/L. In other words, a “Salt-2″ will taste WEAKER in a three-part solution, than in a two-part solution.
The written instructions DO tell you to FIRST, separate the solutions into two-part and three-parters, and then analyze the components. This is a good tip. However, if you don’t realize the dilution is happening (which, frankly NOBODY does), then you’re going to find it much more difficult.
THE TIP :
The best advice is DO NOT use the test Parts 1 & 2 as any sort of reference except for calibrating yourself to the relative relation between various tastes and strengths. In other words, Parts 1 & 2 will give you a general idea about how different the strengths are from each other, and about what each component tastes like. Part 3 should be considered a COMPLETELY NEW test.
In other words, if during Part 3, you search for the Salt-2 or Sweet-3 or Sour-1 that you remember from test Parts 1 and 2, you’ve been tricked. They don’t exist anymore. Forget those. Write them a card if you miss them, but let them go.
First, taste each solution and for each, ask yourself, “Do I taste salt? Do I taste sweet? Do I taste sour?” and check each off on your worksheet. Then, separate the two-part solutions from the three-part solutions. You should have four of each. THESE TWO GROUPS SHOULD ALSO BE CONSIDERED SEPARATELY FROM EACH OTHER.
Start with the two-part solutions now. Find the strongest component you can find. It might be a sweet, sour or salt. This is going to be a level-3 strength. Now recalibrate your brain to think of that as the level-3, and extrapolate downwards in your mind, re-imagining the level-2 and level-1 strengths. There will be at least one or two level-3 components of some sort, but there might not be a level-3 for all three components. Don’t over-think it, but proceed through each solution.
Then, erase that experience from your mind, and proceed to the three-part solutions. Same thing: Find the strongest component you can find. It might be a sweet, sour or salt. This is going to be a level-3 strength. Now recalibrate your brain to think of that as the level-3, and extrapolate downwards in your mind, re-imagining the level-2 and level-1 strengths. There will be at least one or two level-3 components of some sort, but there might not be a level-3 for all three components. Don’t over-think it, but proceed through each solution.
This will set you up for the best chances to pass the dreaded Sensory Skills Test. Good luck!
Summary: World Coffee Events/SCAE Competition Wrap-Up, “The SPRUDGE Radio Minute,” we talk about the recent Twitter debacle, “At The Cupping Table” with Trish and Colleen, and we answer a couple of calls and discuss grinders and hipsters in coffee.
Duration: 1h 16m 10s
I wasn’t there, but I watched online. Looked AMAZING from where I was sitting! Congrats all, especially Alejandro!!!
By no means the most deserving of accolades, but want to highlight the first live audio commentary pilot programming, courtesy Peter Giuliano and James Hoffmann. People have complained for years that the competitions aren’t very engaging to watch. What Peter and James added was a lot of what’s missing, and it was a great peek at what’s possible in the future. LOTS of notes for WBC 2012 Vienna!
That is all.